Bayes' Theorem and The Jesus Family Tomb
Bayes' Theorem and The Jesus Family Tomb
Publication of the book The Jesus Family Tomb in late February, 2007, sparked a media firestorm. Could it be that the actual tomb of Jesus of Nazareth had been found in a suburb of Jerusalem? The book's authors, Simcha Jacobovici and Charles Pellegrino, believe it has. The book was followed up by the showing of a related documentary on the Discovery Channel on March 4, 2007.
The reaction to the book/documentary has been intense, and things got particularly hot around the blogosphere. A number of folks criticized the probabilities quoted by Simcha and Charlie in the book. They alleged that the odds were "600 to 1" that this is in fact the tomb of Jesus of Nazareth. As support, they cited the calculations of Prof. Andrey Feuerverger, of the University of Toronto.
I read the book as soon as I could get a copy and thought hard about Dr. Feuerverger's calculations. Because I have extensive experience in computing probabilities of such "remarkable events," I did my own set of calculations and posted them on this web site in an article titled "Statistics and the Jesus Family Tomb." My conclusion was that the tomb seemed very unlikely to be the family tomb of Jesus of Nazareth."
The article quickly earned a lot of notice around the web, even getting me several mentions on the blogs of Dr. James Tabor and Dr. Mark Goodacre, two noted scholars.
Shortly after my article appeared, I received an email from Jay Cost, a graduate student in political science at the University of Chicago. Jay had written an influential article on the Real Clear Politics web site noting the importance of Bayes' Theorem to the issue. In his email to me, Jay reiterated his comments on Bayes' theorem and also asked some pointed questions about my calculations.
That email prompted a long and intense discussion between me and Jay on the statistics of the Jesus family tomb. At first, I was skeptical of his comments, but after doing some analysis, I quickly decided that he was correct -- there was more to say about the Jesus family tomb. After many hours of talking, we have fused his ideas with mine. I can now report our conclusions.
I should note that Jay also introduced me to Dr. James Tabor, one of the leading players mentioned in the book The Jesus Family Tomb. Prof. Tabor has strongly urged the academic community to give the tomb hypothesis a fair chance.
I agree. There is nothing to gain by dismissing the whole idea out of hand, merely because it was proposed by a documentary producer. Either the tomb once contained the body of Jesus of Nazareth or it didn't. Dr. Tabor and I agree that the issue needs to be studied carefully, without fear of where it will lead. We disagree on a number of issues, but he has become a valued friend. Jay and James have also introduced me to a number of other experts on the subject. And a few other experts took the initiative to contact me. Those folks have helped me define what is generally agreed on and what points are subject to judgment calls.
Jay Cost and I have written a detailed report of our analysis and conclusions, which we have published as a PDF file titled: "He Is Not Here" Or Is He? Along with this article, I created a spreadsheet that does all the calculations described in our article. You can easily change the assumptions in the calculations by adjusting numbers in the spreadsheet to see how it affects the results.
Download the PDF document "He is Not Here" Or Is He? to read our detailed analysis.
Download the Excel spreadsheet JesusCalculations.xls to replicate our calculations.
The article is unfortunately a bit technical. If you don't want to read through all the math, then this page will summarize the line of argument and show you some selected conclusions.
A Review of the Evidence
It's impossible to describe ALL the evidence for the alleged Jesus family tomb. Here, I'm going to review those parts of the evidence that I want to model mathematically.
In 1980, an ancient tomb was found in Jerusalem containing 10 ossuaries. Since ossuaries were only used from about 20 B.C. until A.D. 70, we can assume the bodies belong to Jerusalem residents from that era. We can also assume that this was a FAMILY tomb, because the usual practice then was to bury several generations of families in the tomb over the course of time.
The tomb was excavated by several Israeli archaeologists, including Joseph Gath, Amos Kloner, and Shimon Gibson. Gath died a year later, but Kloner and Gibson are well-known Israeli archaeologists who remember the excavation.
Of the 10 ossuaries, 6 were inscribed with names. These names read:
- Jesus son of Joseph (Aramaic: Yeshua bar Yehosef)
- Mary (Aramaic: Maryah)
- Mary (Greek: Mariamenou e Mara)
- Joseph (Aramaic: Yoseh)
- Matthew (Aramaic: Matyah)
- Judah son of Jesus (Aramaic: Yehudah bar Yeshua)
The "Jesus" name is badly scratched and nearly illegible, but most scholars agree that it should be read as Jesus. The inscription "Judah son of Jesus" is VERY legible, and that convinced the excavators that the "Jesus" inscription was really Jesus.
The Greek inscription "Mariamenou e Mara" has provoked a LOT of controversy. "Mariamenou" is a rare form of the name Mary. It is in the genitive case (it's a possessive) of the diminutive name "Mariamenon". So the best translation of this might be "Belonging to little Mary" or "Belonging to dear Mary." The center word "e" is taken by many scholars to be an abbreviation for "aka". There is a question of how to read "Mara". This is a known abbreviation of "Marta". But it could also be translated as a feminine form of "Master". The masculine form would be "Mar" and this is the common equivalent for "Mr." today in Israel.
In the book The Jesus Family Tomb, Simcha and Charlie argue that this inscription should be read "Belonging to Mariamenou, also known as The Master." They further argue that Mariamne was the "real" name of Mary Magdalene, as proved by the fourth-century Gnostic book "The Acts of Philip." They quote Dr. Francois Bovon of Harvard University to support their claim that Mary Magdalene's real name was Mariamne. A critical point of Simcha and Charlie's thesis is that the inscription "Mariamenou e Mara" should be understood, with very high probability, to be "Mary Magdalene."
Most scholars flatly disagree. There are numerous problems, which I reviewed in my previous article. Since this an important issue, I'll review them here:
- As Dr. Bovon has said in one of his articles on the subject, "I do not believe that Mariamne is the real name of Mary of Magdalene."
- The Acts of Philip is nearly four full centuries after the time of Jesus, and it has no historical value. It's fiction.
- The "Mariamne" in the Acts of Philip is ALSO identified at the same time as Mary of Bethany. But Mary of Bethany is an entirely different historical person than Mary Magdalene.
- "Mariamne" is in fact a fairly common variant form of Mary. King Herod the Great had a wife whose name is spelled both "Mariamne" and "Mariamme" in different sources.
- The name on the ossuary is in fact "Mariamenon", not "Mariamne".
- In the New Testament, Mary Magdalene's name is spelled "Maria", exactly the same spelling as Mary the mother of Jesus, and Mary of Bethany. There is no reason to believe that "Mariamenon" was a unique identifier for Mary Magdalene.
For all of these reasons, it's really impossible to argue that the ossuary inscribed "Mariamenou e Mara" must have once contained Mary Magdalene. This is a historical question to be resolved by New Testament scholars. Since I'm not a New Testament scholar, I'll simply repeat what the consensus is. "Mariamenou e Mara" could be ANY Mary who lived in ancient Jerusalem. There is no reason to connect this name to Mary Magdalene.
Of course, it is POSSIBLE that the "ariamenou e Mara" ossuary contains Mary Magdalene. We can't rule that out. All we can say is that this particular form of the name Mary does not make it MORE likely to refer to Mary Magdalene.
We note here that DNA evidence shows that the "Jesus" ossuary and the "Mariamenou e Mara" ossuary are not maternally linked. So "Mariamenon" is not the mother or sister of the Jesus of the tomb. Most likely, "Mariamenon" is connected to the family by marriage. She might be the wife, sister-in-law, aunt, niece, or other in-law relation of the Jesus of the tomb.
There are many who would ask at this point, why in the heck are we even talking about this? Isn't it obvious that Jesus of Nazareth was raised from the dead and ascended to heaven and that his body can't possibly be buried in some tomb somewhere?
Well, yes, it's "obvious" to most Christians. The problem is that it's not at all obvious to anyone else. That is a faith assertion. Many Christians would argue that it's a faith assertion backed by solid historical evidence. Still, it's a faith assertion. In this article, I'll show how to do the calculations so that you either use this faith assertion or you don't -- it's up to you.
Aside from faith assertions, there are some strong reasons to question whether Jesus of Nazareth could possibly be buried in this particular tomb. I'll refer you to Dr. Jodi Magness' article "Has the Tomb of Jesus Been Discovered?". Even if Jesus was NOT raised from the dead, Dr. Magness argues that this particular family tomb is a poor candidate for his final resting place.
This is not a faith assertion, it is a historical judgment, and a disputed judgment at that. I'll show how to account for this historical judgment in our calculations. You can make your OWN judgment on this issue and see the results for yourself.
The Tomb Hypothesis
Based on the above evidence, Simcha Jacobovici and Charles Pellegrino hypothesized that the tomb might be the tomb for the family of Jesus of Nazareth. They believed that this would not upset many Christians. They guessed wrongly on that. Many Christians got VERY upset.
But tempers have no place in a scientific investigation. The question is a valid one to ask: Could this be the family tomb of Jesus of Nazareth? What are the odds?
We have only the following to help us estimate the odds:
- The evidence of the tomb
- Historical judgments
- Faith assertions
Please note that there is some fuzziness here, since BOTH historical judgments AND faith assertions are subjective elements -- which we'll call "fuzzy factors". But the evidence of the tomb is pretty darned objective. Wouldn't it be interesting if the evidence of the tomb was strong enough to make a decision REGARDLESS of the fuzzy factors?
We'll see if that's possible. But let's forge on ahead. The reason we suspect that this tomb might POSSIBLY be the family tomb of Jesus of Nazareth is that so many of the names are familiar to us from the Gospels. Jesus had a mother named Mary. Probably 3 or 4 other women in his inner circle were also named Mary. Jesus' father was named Joseph. He had four brothers named James, Joseph, Judah, and Simon. He also had at least two sisters, traditionally known as Mary and Salome. Unfortunately, we can't say how good those traditions are, since they don't go back to first-century sources.
We should note that Matthew is both the name of a disciple of Jesus AND a great-grandfather. Most historians don't consider this relevant. A family tomb typically contained people of the extended family, including slaves. There is no particular reason to expect the disciples of a rabbi to be buried in his family tomb. Nor is there good reason to expect a great-grandfather from Nazareth to be dislocated. So the consensus on all sides is to ignore Matthew.
An important point is that history knows nothing of any children of Jesus of Nazareth. The Jesus of the tomb had a son named Judah. It is POSSIBLE that Jesus of Nazareth had a son that we never heard about. But how probable is it? Once again, we're faced with a judgment call, yet another "fuzzy factor" that we need to deal with.
Is the math going to be able to handle all these fuzzy factors? Maybe. Maybe not. The only way to know is by doing the calculations. Let's consider a couple of "extreme cases" in order to see some examples of when the math would be pretty definite.
The Calculus of Jesus
Suppose that the tomb was just outside the walls of first-century Jerusalem and had the following names inscribed on the ossuaries:
- "Mary, mother of Jesus"
- "James, son of Joseph, brother of Jesus, from Nazareth"
- "Judah, son of Joseph"
- "Joseph son of Joseph, brother of Jesus"
- "Simon, son of Joseph, from Nazareth"
- "Mary of Magdala"
Wouldn't you agree that this would be FREAKIN' GOOD EVIDENCE that you'd found the family tomb of Jesus? Yes, you would. Why? Because this is a virtually perfect match to the historical record. It agrees with many known facts. It doesn't disagree with any known facts. The only thing that could make it stronger would be if the Mary, Judah, and Joseph inscriptions also said "from Nazareth" and if the Judah and Simon inscriptions specified "brother of Jesus". But honestly, that level of corroboration isn't necessary. And nobody would quibble about including Mary Magdalene in the tomb, even if she wasn't part of the immediate family. Since Mary was a wealthy woman, it would be plausible that she paid for the tomb. If we found this tomb, every reasonable person would agree that the tomb matches the historical record almost exactly.
The point here is that names are good indicators, but it's far more convincing to see the relationships spelled out too. And a couple of place names to indicate where these people came from is even stronger yet. Ossuaries sometimes do give these kinds of information.
Suppose instead that the tomb was in Chicago and had the following names inscribed on the ossuaries:
- "Douglas son of Raymond"
- "Lizzie, native Chicagoan"
- "Bilbo Baggins"
- "Ricardo son of Douglas, Cubs fan"
Is there anybody on the planet who would imagine that this is the family tomb of Jesus of Nazareth? LOL, no way! Why? Because there are no matches. The tomb doesn't match the historical record AT ALL.
Finally, suppose you found a tomb near old Jerusalem that had 10 ossuaries, and all of them were blank! No names at all. Would you leap to the conclusion that this IS DEFINITELY the family tomb of Jesus? [Click here to read the rest of the article ...]